Worcester Bosch Greenstar i System ErP (9i, 12i, 15i, 18i, 21i, 24i)
System boiler, natural gas and LPG
Combustion figures
| Figure | Natural gas (G20) | LPG (G31) |
|---|---|---|
CO₂ at high rate More infoHide infoFrom Tables 43 and 44 (MI 7.5), maximum setting, measured after 10 minutes in chimney sweep mode, case on. The technical data (MI 3.2, Tables 4 and 5) gives 9.8% (NG) and 11% (LPG) at maximum, after 10 minutes. The MI says not to adjust the air/gas ratio valve: the gas valve is factory set and must not be adjusted during commissioning if found out of tolerance (MI 6.5). If CO₂ is still out of tolerance after all the checks in MI 7.5, the gas valve must be replaced. | Between 9.0 and 10.8% | Between 10.2 and 11.8% |
CO₂ at low rate More infoHide infoFrom Tables 43 and 44 (MI 7.5), minimum setting, measured after 10 minutes. The technical data (MI 3.2, Tables 4 and 5) gives 9.1% (NG) and 10.5% (LPG) at minimum, after 10 minutes. | Minimum lower than the maximum reading taken but above 8.0% and less than 10.6% | Minimum lower than the maximum reading taken but above 9.5% and less than 11.6% |
Maximum CO More infoHide infoThe manual gives different limits. The combustion check flow chart (MI 6.5.7, Fig. 48) says CO < 350ppm at maximum and minimum rate. The flue gas analysis steps (MI 6.5.9) say CO <200ppm at maximum and minimum, for both gases. Table 43 (NG, MI 7.5) gives less than 200ppm and Table 44 (LPG, MI 7.5) gives less than 250ppm, at maximum and minimum. All shown as printed. |
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CO/CO₂ ratio More infoHide infoThe manual gives two limits. The combustion check flow chart (MI 6.5.7, Fig. 48) says CO/CO₂ ratio < 0.004 at maximum and minimum rate. The flue gas analysis steps (MI 6.5.9) say <0.002 at maximum and minimum. MI 6.5.3 says the technical data gives CO/CO₂ ratios, but Tables 4 and 5 don’t list one. |
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O₂ | Not given in MI | Not given in MI |
Working inlet pressure More infoHide infoFrom Table 34 and Figs. 46 and 47 (MI 6.5.2), appliance running at maximum in chimney sweep mode (MI 6.5.1). At the meter: NG 19–23 mbar. At the regulator: LPG 32–45 mbar. Allowed drop across the pipework: 1 mbar (NG), 2.5 mbar (LPG); across the appliance: 1.5 mbar. The drop from the meter or regulator to the gas valve must be no more than 2.5 mbar (NG) or 4 mbar (LPG). |
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Gas rate at maximum More infoHide infoMax. 10 minutes from lighting, NG figures for G20 (MI 3.2, Tables 4 and 5, where the sizes are headed 9kW to 24kW). Measure at the gas meter after at least 10 minutes at maximum output in service mode (MI 6.5.3). Where there’s no gas meter (e.g. LPG), check CO/CO₂ instead. |
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Flue integrity More infoHide infoAt the air inlet sample point on the flue turret or adaptor, appliance case on, appliance running at maximum, readings allowed to stabilise (MI 6.5.8). Readings outside these limits mean a problem with the flue system or combustion circuit. | O₂ ≥ 20.6% CO₂ < 0.2% | O₂ ≥ 20.6% CO₂ < 0.2% |
From 6 720 806 945 (2015/07)
Enter service mode for high and low rate
High rate
- Hold the Reset/Service engineer button (chimney sweep symbol under it) for at least 5 seconds.
- Chimney sweep symbol shows at the top, Max flashes at the bottom and the button stays lit. It goes to maximum by itself.
Low rate
- Press the DHW ▼ button (right-hand pair) for minimum. Min shows at the bottom of the display.
Ending the test
- Press the Reset/Service engineer button (or the Info/Return button) to come out. It also ends by itself after 15 minutes.
- If a service reminder is set, Reset service reminder timer (Yes/No) shows when you come out.
Models and GC numbers
| Model | GC number | Gas |
|---|---|---|
| Greenstar 9i System ErP | 41-406-21 | NG |
| Greenstar 12i System ErP | 41-406-23 | NG |
| Greenstar 15i System ErP | 41-406-25 | NG |
| Greenstar 18i System ErP | 41-406-27 | NG |
| Greenstar 21i System ErP | 41-406-29 | NG |
| Greenstar 24i System ErP | 41-406-31 | NG |
| Greenstar 9i System ErP LPG | 41-406-22 | LPG |
| Greenstar 12i System ErP LPG | 41-406-24 | LPG |
| Greenstar 15i System ErP LPG | 41-406-26 | LPG |
| Greenstar 18i System ErP LPG | 41-406-28 | LPG |
| Greenstar 21i System ErP LPG | 41-406-30 | LPG |
| Greenstar 24i System ErP LPG | 41-406-32 | LPG |
Source: Greenstar i System ErP wall hung RSF gas fired condensing system boiler installation, commissioning and servicing instructions, 6 720 806 945 (2015/07).
Sections: Cover (GC numbers); 3.2 Technical data; 6.5 Commissioning; 6.5.1 Checking the gas inlet pressure; 6.5.2 Gas pressure within the system; 6.5.3 Checking the gas rate; 6.5.4 Gas rate testing; 6.5.7 CO and combustion checks; 6.5.8 Checking flue integrity; 6.5.9 Flue gas analysis; 7.3 Check the gas inlet pressure; 7.5 Flue gas analysis.
Spotted something wrong? Tell us.
Check these figures against the MI for the appliance in front of you, matched by GC number and manual date. Combustion work needs a calibrated analyser and a Gas Safe registered engineer.